Khanna A.S. (Ed.) High-Performance Organic Coatings: Selection, application and evaluation
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Contents xi
17.5 Future of coil coating 384
17.6 References and further reading 385
18 High-performance organic coatings for wastewater
treatment plants 388
D D
HAGE, EWAC Alloys Ltd., India
18.1 Introduction 388
18.2 Categories of waste treatment plants 389
18.3 Materials of construction and their deterioration 392
18.4 Protection by coatings 394
395
18.6 399
18.7 Application of various resins 400
18.8 Formulation issues 400
402
18.10
coatings 404
treatment plants 404
18.12 Conclusions 405
18.13 References 406
19 Anticorrosion organic coatings for the
automotive industry 407
M G MEHROTRA, Kansai Nerolac Paints Ltd, India
19.1 Introduction: automotive coatings 407
19.2 Types of automotive coating 409
19.3 Sequence for coating automobile body shells 411
19.4 Detailed methodology of primers, basecoats and topcoats
414
19.5 Anti-scratch and anti-mar coatings 417
19.6 Special coatings for plastic and other non-metallic
components 420
19.7 Future developments in automotive coatings 420
19.8 Application and process systems 422
19.9 Nanomaterials as additives in coatings 423
19.10 Nanocomposites in surface coatings 425
19.11 Incorporation of inorganic particles and clusters for
hybrid coatings 426
19.12 Self-cleaning paint layers 426
19.13 Abrasion-resistant coatings 426
19.14 Non-chromate corrosion inhibitors 426
19.15 Conclusions 427
19.16 References 427
and metallic finishes
18.5 Glassflake-filled coating systems
Different resin systems for glassflake coatings
18.9 Advantages of glassflake coatings
Performance of glassflake-filled coating against conventional
18.11 Application of glassflake coating to wastewater
© 2008, Woodhead Publishing Limited
xii Contents
20 Using organic coatings for repainting and
maintenance of steel components and structures 429
MJ M
ITCHELL and N WILDS, International Paints Ltd, UK
20.1 Introduction 429
20.2 Conventional systems 430
20.3 Developments in conventional coatings 432
20.4 ‘High-performance’ coatings 433
20.5 Alternative approaches 434
20.6 Complete surface tolerance 434
20.7 Urethane surface tolerance 436
20.8 Epoxy ‘mastics’ 437
20.9 Current development 438
20.10 Moisture-cured urethanes (MCUs) 438
20.11 Rust converters 439
20.12 Conclusions 440
© 2008, Woodhead Publishing Limited
Contributor contact details
xiii
(* = main contact)
Introduction, Chapters 1, 2,
3, 5, and 14
Professor A. S. Khanna
Department of Metallurgical
Engineering and Materials
Science
Indian Institute of Technology
Bombay
Bombay – 400 076
India
E-mail: khanna@iitb.ac.in
Chapter 4
Professor A. S. Khanna*
Department of Metallurgical
Engineering and Materials
Science
Indian Institute of Technology
Bombay
Bombay – 400 076
India
E-mail: khanna@iitb.ac.in
S. Kumar
J.K. Surface Coatings
48/9, Neel Siddhy Complex
New Bombay-400703
India
E-mail: santogh.kumar@iksc.in
Chapter 6
Dr B. P. Mallik
Asian Paints Limited
Asian Paints House
6A Shantinagar
Vakola Pipeline Road
Santacruz (East)
Mumbai 400 055
India
E-mail: bp.mallik@asianpaints.com
Chapter 7
Department of Materials
Engineering and Industrial
Technologies
University of Trento
Via Mesiano 77
38050 Trento
Italy
E-mail: stefano.rossi@ing.unitn.it
S. Rossi* and F. Deflorian
© 2008, Woodhead Publishing Limited
Chapter 8
Sameer S. Kanitkar
Aditya Birla Chemicals (Thailand)
Ltd
Epoxy Division
I-5 Road, IEAT no. 2
Map Ta Phut Industrial Estate
Map Ta Phut, Rayong – 21150
Thailand
E-mail: samir.kanitkar@adityabirla.
com
Chapter 9
Dr K.V.S.N. Raju*
Organic Coatings and Polymers
Division
Indian Institute of Chemical
Technology
Tarnaka
Hyderabad – 500007
India
Email:kvsnraju@iict.res.in
drkvsnraju@gmail.com
D.K. Chattopadhyay
Research Associate
Department of Coatings and
Polymeric Materials
North Dakota State University
1735 Research Park Drive
Fargo, ND 58105
USA
Chapter 10
G. Greenwood-Sole
Corrocoat Limited
Forster Street
Leeds
West Yorkshire LS10 IPW
UK
E-mail: grahams@corrocoat.com
xiv Contributor contact details
Chapter 11
Abdul Salem Hamdy
Department of Surface Technology
and Corrosion Protection
Central Metallurgical Research
and Development Institute
(CMRDI)
PO Box 87
Helwan, 11421 Cairo
Egypt
E-mail: ashamdy@cmrdi.sci.eg
Chapter 12
K-H. Kaesler
Momentive Performance Materials
Inc.
Leverkusen
Germany
E-mail: karl-heinz.kaesler@
momentive.com
Chapter 13
Professor A.S. Khanna and
S.S. Pathak
Department of Metallurgical
Engineering and Materials
Science
Indian Institute of Technology
Bombay
Bombay – 400 076
India
E-mail: sspathak@iitb.ac.in
khanna@met.iitb.ac.in
© 2008, Woodhead Publishing Limited
Chapter 15
Mr Narendra Kumar
GAIL (India) Ltd
A.V. Apparao Road
Rajahmundry – 533103
Andhra Pradesh
India
E-mail: nkumar@gail.co.in
Chapter 16
J.H.W. de Wit* and J.M.C. Mol
Delft University of Technology
Department of Materials Science
and Engineering
Mekelweg 2
2628 CD Delft
The Netherlands
Email: j.h.w.dewit@tudelft.nl
W.M. Bos and G. M. Ferrari
TNO Science and Industry
PO Box 505
1780 AM Den Helder
The Netherlands
Chapter 17
Maria Eliziane Pires de Souza
Faculty of Mechanical Engineering
University of Campinas
Street: Mendeleiev s/n
Cidade Universitária ‘Zeferino
Vaz’ Barão Geraldo
Campinas – SP
P. O. Box 6122
CEP: 13.083-970
Brazil
E-mail: eliziane@fem.unicamp.br
Contributor contact details xv
Chapter 18
Dhananjay Dhage
R & D Center
Larsen & Toubro
EWAC Alloys Limited
L & T gate No 3
Bombay – 400 076
India
Email: drd-ewac@powai.ltindia.
com
dhananjaydhage@yahoo.com
Chapter 19
Mr M. G. Mehrotra
Kansai Nerolac Paints Ltd
Nerolac House
Ganpatrao Kadam Marg
Lower Parel
Mumbai – 400 013
India
Email: maheshmehrotra@nerolac.
com
Chapter 20
MJ Mitchell and Neil Wilds
Technical Manager – Worldwide
Protective Coatings
International Paints Ltd
Stoneygate Lane
Felling NE10 0JY
UK
E-mail: neil.wilds@
internationalpaint.com
© 2008, Woodhead Publishing Limited
Introduction
A S KHANNA, Indian Institute of Technology Bombay, India
xvii
Corrosion is a natural process and many metals and alloys used in industrial
applications need protection in order to minimize or prevent corrosion.
There are various methods of corrosion control which include better design,
choice of better materials, protection by inhibitors, cathodic and anodic
protection, and protection by coatings. Among these, coating is the simplest
and most widely used method.
Steel is used all over the globe in a huge number of applications. Steel,
however, is a very reactive material even in normal environmental condi-
tions, corroding in moist air. It needs protection wherever it is used. Whether
it is a steel structure, steel frame, steel tank, overhead steel pipe or under-
ground cross-country pipeline, all need corrosion protection. The most
common method to protect steel from corrosion is paint coatings.
A paint coating is basically a polymer resin, dispersed in a solvent, modi-
colour, corrosion protection and other important properties. The nature of
the coating revolves round the type of resin that is used, whether alkyd,
epoxy, urethane, vinyl or polyester. High-performance properties can be
achieved by adding different kinds of pigments, which give not only colour
and opacity but also strength, lower permeability and, in turn, longer life.
High performance can also be achieved by using solventless systems which
not only give higher thickness per coat but also are environmentally friendly
because of their low volatile organic content (VOC).
Any discussion of coating is incomplete unless it considers surface prepa-
ration and paint application. Surface preparation is a key aspect of paint
coatings: any mistake at this stage will compromise the coating. It is advis-
able to carry out proper surface preparation by following a suitable stan-
tolerant coatings able to cope with partially cleaned surfaces, are important
fied by additives to achieve specific properties and pigments for providing
dard and measuring its anchor profile. New paint formulations or surface
requirements for maintenance of offshore structures, chemical plants, refin-
eries and power plants where surface cleaning may be difficult.
© 2008, Woodhead Publishing Limited
Paint application has become a very specialized subject. Today it is
important to know about not only traditional methods of paint application
by brush and roller but also the use of more sophisticated techniques such
as airless spray, electrostatic powder application, together with the special
application skills required to apply elastomeric polyurethane, polyurea and
many other fast-curing polyester coatings. Methods for the maintenance of
paint coatings are also increasingly important.
Despite proper application, paint coatings do fail prematurely. It is very
important to understand what causes the paint to fail and what the various
remedial measures are. Another issue in paint coatings is to estimate the
life of the coating. It is very important to correctly estimate paint life. Are
conventional testing techniques adequate or do we need new methods to
estimate the life of a coating? Lastly, it is essential to incorporate good paint
inspection and quality assurance techniques both during paint application
and afterwards. The importance of supervisors, coating inspectors and
others responsible for maintaining quality should be emphasized. They
should be provided with good theoretical and practical training.
This book covers a range of key issues in the effective use of high-
performance organic paint coatings, including important industrial applica-
tions, offshore structures, underground pipelines, automotive coatings, coil
coatings, coatings for rebars and concrete structures, coatings for ships and
in other aggressive environments.
xviii Introduction
© 2008, Woodhead Publishing Limited
Part I
General issues
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3
1
Key issues in applying organic paint coatings
A S KHANNA,
Indian Institute of Technology Bombay, India
1.1 Introduction
A paint coating can be best described as a coating system, which consists
of four main stages:
• Surface preparation
• Primer application
• Application of an intermediate coat
• Application of a top coat.
For any coating to be effective, all four steps are essential. Negligence in
performing any of the above steps can reduce coating performance and
service life. Surface preparation is the most important of these stages. This
topic will be discussed in the next chapter.
The role of primer is very important. An organic coating applied without
a primer may act as a barrier coating. However, severe corrosion can occur
to the substrate if the coating is damaged. In the presence of a suitable
primer, such corrosion of the substrate can be prevented. As an example, a
zinc-based primer, applied before the main coating, protects the substrate
from corrosion through a cathodic protection mechanism, in case the
coating becomes damaged during service. There are several other advan-
tages of the primers which will be discussed in the following section.
An intermediate coat is the main coating which provides barrier protec-
tion to the substrate. The intermediate coating may be applied as one coat or
more, depending upon the severity of the environment. The top coat can
sometimes be the intermediate coat only. However, if the intermediate coat
is an epoxy or any other coating which is UV sensitive, it must have a top coat
which is UV resistant. Further details are given in the following sections.
1.2 Primers
are several advantages of primers:
A primer is defined as a first coat before the main coating is applied. There
© 2008, Woodhead Publishing Limited
4 High-performance organic coatings
• A primer application can provide a corrosion-resistant barrier.
• For thin sheets and strips, where shot blasting is not possible because of
bending of the strip, a primer application can act as a means to create
a suitable rough surface. This is usually achieved by conversion coatings,
such as phosphating or chromating coatings. The process involves clean-
ing the specimen, followed by dipping it in a suitable chromate or phos-
phate solution, which converts the surface of the steel substrate to a
phosphate or chromate of iron.
• In the case of a partially cleaned surface, primer application is essential
to improve the wetting properties of the surface.
Most of the primers used for providing corrosion resistance to the coating
are zinc-based. Several reviews have highlighted the importance, advan-
tages and limitations of these primers and their difference from alternative
techniques such as conventional hot dip galvanization [1–3]. Zinc-rich coat-
ings are of two types:
• Organic zinc-rich coatings
• Inorganic zinc silicate coatings.
An organic zinc-based coating is usually a dispersion of zinc dust in an
organic resin. The organic resin may be alkyd, epoxy or polyurethane and
is usually used as a base for the corresponding organic coating. It is usually
a colloidal solution of zinc in the organic resin as shown in Fig. 1.1. The
bonding of the coating is resin based. The performance of an organic zinc-
rich coating depends upon the amount and purity of zinc dust used. A small
amount of zinc dust can give a coating some inhibitive properties. However,
cathodic protection is achieved only when the zinc dust concentration is
more than 75% by weight.
An organic zinc coating can be single-component or two-component. A
two-component coating is more effective than a single-component coating.
Other organic zinc-rich coatings can be made by the addition of zinc phos-
phate in an organic resin. Such coatings can be applied on the fully cleaned
or partially cleaned surfaces.
Conduction through metallic substrate
Conduction through zinc dust particle
Zinc dust particle
Metallic substrate
1.1 Effect of zinc on the coating performance of the organic resin.
Zinc primer film
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